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United States Patent |
5,727,101
|
Giebel
,   et al.
|
March 10, 1998
|
Monolithic ferrule for receiving and positioning multiple optical fibers
and an optical fiber connector incorporating same
Abstract
An optical fiber connector includes a connector housing and a monolithic
ferrule disposed within the connector housing for maintaining a plurality
of optical fibers in respective predetermined positions relative to the
connector housing. The monolithic ferrule includes a monolithic ferrule
body defining an internal cavity and a plurality of longitudinal bores
through which the optical fibers extend. The optical fiber connector can
also include an annular alignment key extending radially outward from the
monolithic ferrule and having a position indicator adapted to mate with
the connector housing such that the monolithic ferrule is held in a
predetermined position relative to the connector housing. Accordingly, the
optical fibers secured within the monolithic ferrule can be held in
respective predetermined positions relative to the connector housing. The
alignment key can be formed from the same piece of material from which the
monolithic ferrule body is formed such that the alignment key is an
integral part of the monolithic ferrule. The monolithic ferrule can also
include ferrule alignment means for aligning the monolithic ferrule with
another ferrule such that the optical fibers received by the longitudinal
bores defined by the monolithic ferrule are aligned with the optical
fibers secured within the other ferrule, thereby increasing the efficiency
with which optical signals are transmitted therebetween.
Inventors:
|
Giebel; Markus A. (Conover, NC);
Luther; James P. (Hickory, NC)
|
Assignee:
|
Siecor Corporation (Hickory, NC)
|
Appl. No.:
|
540288 |
Filed:
|
October 6, 1995 |
Current U.S. Class: |
385/59 |
Intern'l Class: |
G02B 006/38 |
Field of Search: |
385/60-68,72,78-85
|
References Cited
U.S. Patent Documents
3846010 | Nov., 1974 | Love et al. | 385/55.
|
4405200 | Sep., 1983 | Hoffmann et al. | 385/59.
|
4685765 | Aug., 1987 | Daly et al. | 385/70.
|
4699458 | Oct., 1987 | Ohtsuki et al. | 385/59.
|
4708433 | Nov., 1987 | Kakii et al. | 385/59.
|
4763978 | Aug., 1988 | Courtney-Pratt et al. | 385/54.
|
4898449 | Feb., 1990 | Vroomen et al. | 385/114.
|
4978377 | Dec., 1990 | Brehm et al. | 385/87.
|
4989946 | Feb., 1991 | Williams et al. | 385/16.
|
5064268 | Nov., 1991 | Morency et al. | 385/126.
|
5093881 | Mar., 1992 | Bortolin et al. | 385/56.
|
5123072 | Jun., 1992 | Kawanami et al. | 385/64.
|
5125055 | Jun., 1992 | Kawanami et al. | 385/59.
|
5157749 | Oct., 1992 | Briggs et al. | 385/60.
|
5214730 | May., 1993 | Nagasawa et al. | 385/58.
|
5257333 | Oct., 1993 | Nodfelt | 385/58.
|
5353365 | Oct., 1994 | Dumas et al. | 385/51.
|
5384875 | Jan., 1995 | Shannon et al. | 385/102.
|
Foreign Patent Documents |
62-19821 | Jan., 1987 | JP | 385/59.
|
62-247308 | Oct., 1987 | JP | 385/59.
|
1-120511 | May., 1989 | JP | 385/59.
|
2-55312 | Feb., 1990 | JP | 385/59.
|
Primary Examiner: Ngo; John
Claims
That which is claimed is:
1. An optical fiber connector comprising:
a connector housing having opposed first and second ends and defining an
internal cavity opening through both the first and a monolith
a monolithic ferrule for maintaining a plurality of optical fibers in
respective predetermined positions relative to said connector housing,
said monolithic ferrule comprising a monolithic ferrule body extending
longitudinally between opposed first and second ends and disposed within
the internal cavity of said connector housing such that the first end of
said monolithic ferrule body is exposed through the first end of said
connector housing, said monolithic ferrule body also defining an internal
cavity for receiving the plurality of optical fibers, wherein the internal
cavity opens through the second end of said monolithic ferrule body and
extends longitudinally through at least a portion of said monolithic
ferrule body, said monolithic ferrule body also defining a plurality of
longitudinal bores extending between the first end of said monolithic
ferrule body and the internal cavity defined therein, wherein the
longitudinal bores are adapted to receive respective ones of the plurality
of optical fibers such that the optical fibers are maintained in
respective predetermined positions relative to the monolithic ferrule
body; and
an annular alignment key mounted to said monolithic ferrule and extending
radially outward, wherein said alignment key includes a position indicator
and is adapted to mate with said connector housing such that said
monolithic ferrule is held in a predetermined position therein, and
wherein the plurality of longitudinal bores are positioned in a
predetermined angular relationship to the position indicator of said
alignment key such that the optical fibers received by the longitudinal
bores are maintained in respective predetermined positions to said
connector housing.
2. An optical fiber connector according to claim 1 wherein said monolithic
ferrule further comprises said annular alignment key such that said
alignment key is an integral portion of said monolithic ferrule body.
3. An optical fiber connector according to claim 1 further comprising:
a ferrule sleeve having opposed first and second ends and defining a bore
extending longitudinally therethrough such that a first end of said
ferrule sleeve is capable of being mounted about at least a portion of
said monolithic ferrule and such that a second end of said ferrule sleeve
is capable of being mounted about at least a portion of a ferrule of
another optical fiber connector; and
interlocking means for rotatably engaging said ferrule sleeve and the
ferrule bodies about which said ferrule sleeve is mounted such that the
rotatably engaged ferrule bodies are maintained in a predetermined aligned
relationship.
4. An optical fiber connector according to claim 3 wherein said
interlocking means comprises:
a slot defined by said monolithic ferrule body and extending both radially
inward and longitudinally along an exterior surface thereof; and
a rib extending longitudinally along and radially into the bore defined by
said ferrule sleeve to thereby engage a corresponding slot defined by each
of the ferrule bodies such that the ferrule bodies are maintained by said
ferrule sleeve in the predetermined aligned relationship.
5. An optical fiber connector according to claim 1 wherein the internal
cavity defined by said monolithic ferrule body comprises first and second
internal cavity portions adjacent the first and second ends of said
monolithic ferrule body, respectively, and having respective predetermined
sizes, and wherein the predetermined size of the second internal cavity
portion is greater than the predetermined size of the first internal
cavity portion to thereby facilitate the insertion of the plurality of
optical fibers therein.
6. An optical fiber connector according to claim 1 wherein said monolithic
ferrule body comprises a radially tapered nose portion adjacent the first
end of said monolithic ferrule body, said radially tapered nose portion
having an outer diameter which decreases in a longitudinal direction
toward the first end of said monolithic ferrule body to thereby facilitate
connection of the optical fiber connector.
7. A monolithic ferrule for maintaining a plurality of optical fibers in
respective predetermined positions relative to an optical fiber connector,
the monolithic ferrule comprising:
a monolithic ferrule body extending longitudinally between opposed first
and second ends, said monolithic ferrule body defining an internal cavity
for receiving the plurality of optical fibers, wherein the internal cavity
opens through the second end of said monolithic ferrule body and extends
longitudinally through at least a portion of said monolithic ferrule body,
said monolithic ferrule body also defining a plurality of longitudinal
bores extending between the first end of said monolithic ferrule body and
the internal cavity defined therein, wherein the longitudinal bores are
adapted to receive respective ones of the plurality of optical fibers such
that the optical fibers are maintained in respective predetermined
positions relative to the monolithic ferrule body; and
an integral alignment key extending radially outward, wherein said integral
alignment key includes a position indicator and is adapted to mate with
the optical fiber connector such that said monolithic ferrule is held in a
predetermined position therein, wherein the plurality of longitudinal
bores are positioned in a predetermined angular relationship to the
position indicator of said integral alignment key such that the optical
fiber received by the longitudinal bores are maintained in respective
predetermined positions to the optical fiber connector.
8. A monolithic ferrule according to claim 7 further comprising ferrule
alignment means for aligning the monolithic ferrule with another ferrule
such that the optical fibers received by the longitudinal bores defined by
the monolithic ferrule are aligned with the optical fibers secured within
the other ferrule.
9. A monolithic ferrule according to claim 8 wherein said ferrule alignment
means comprises a slot defined by said monolithic ferrule body and
extending both radially inward and longitudinally along an exterior
surface thereof, said slot being adapted to receive a rib extending
longitudinally along and radially into a bore defined by a ferrule sleeve
which is mounted about both the first end of said monolithic ferrule body
and the other ferrule such that the ferrule bodies are rotatably engaged
and thereby maintained by the ferrule sleeve in the predetermined aligned
relationship.
10. A monolithic ferrule according to claim 7 wherein the internal cavity
defined by said monolithic ferrule body comprises first and second
internal cavity portions adjacent the first and second ends of said
monolithic ferrule body, respectively, and having respective predetermined
sizes, and wherein the predetermined size of the second internal cavity
portion is greater than the predetermined size of the first internal
cavity portion to thereby facilitate the insertion of the plurality of
optical fibers therein.
11. A monolithic ferrule according to claim 10 wherein the second internal
cavity portion defined by said monolithic ferrule body further comprises a
radially tapered portion adjacent the second end of said monolithic
ferrule body to further facilitate the insertion of the plurality of
optical fibers therein.
12. A monolithic ferrule according to claim 7 wherein said monolithic
ferrule body comprises a radially tapered nose portion adjacent the first
end of said monolithic ferrule body, said radially tapered nose portion
having an outer diameter which decreases in a longitudinal direction
toward the first end of said monolithic ferrule body.
13. A monolithic ferrule according to claim 7 wherein said monolithic
ferrule body is comprised of a material selected from the group consisting
of thermoplastic material and ceramic material.
14. A ferrule assembly for maintaining a plurality of optical fibers in
respective predetermined positions, the ferrule assembly comprising:
a monolithic ferrule body extending longitudinally between opposed first
and second ends, said monolithic ferrule body defining an internal cavity
for receiving the plurality of optical fibers, wherein the internal cavity
opens through the second end of said monolithic ferrule body and extends
longitudinally through at least a portion of said monolithic ferrule body,
said monolithic ferrule body also defining a plurality of longitudinal
bores extending between the first end of said monolithic ferrule body and
the internal cavity defined therein, wherein the longitudinal bores are
adapted to receive respective ones of the plurality of optical fibers such
that the optical fibers are maintained in respective predetermined
positions relative to the monolithic ferrule body;
a ferrule sleeve having opposed first and second ends and defining a bore
extending longitudinally therethrough such that a first end of said
ferrule sleeve is capable of being mounted about at least a portion of
said monolithic ferrule body and such that a second end of said ferrule
sleeve is capable of being mounted about at least a portion of another
ferrule body; and
interlocking means for rotatably engaging said ferrule sleeve and the
ferrule bodies about which said ferrule sleeve is mounted such that the
rotatably engaged ferrule bodies are maintained in a predetermined aligned
relationship.
15. A ferrule assembly according to claim 14 wherein said interlocking
means comprises:
a slot defined by said monolithic ferrule body and extending both radially
inward and longitudinally along an exterior surface thereof; and
a rib extending longitudinally along and radially into the bore defined by
said ferrule sleeve to thereby engage a corresponding slot defined by each
of the ferrule bodies such that the ferrule bodies are maintained by said
ferrule sleeve in the predetermined aligned relationship.
16. A ferrule assembly according to claim 14 wherein said monolithic
ferrule body further comprises an integral alignment key extending
radially outward therefrom, said integral alignment key including a
position indicator and being adapted to mate with the optical fiber
connector such that said monolithic ferrule body is held in a
predetermined position therein, and wherein the plurality of longitudinal
bores are positioned in a predetermined angular relationship to the
position indicator of said integral alignment key such that the optical
fibers received by the longitudinal bores are maintained in respective
predetermined positions to the optical fiber connector.
17. A ferrule assembly according to claim 14 wherein the internal cavity
defined by said monolithic ferrule body comprises first and second
internal cavity portions adjacent the first and second ends of said
monolithic ferrule body, respectively, and having respective predetermined
sizes, and wherein the predetermined size of the second internal cavity
portion is greater than the predetermined size of the first internal
cavity portion to thereby facilitate the insertion of the plurality of
optical fibers therein.
18. A ferrule assembly according to claim 14 wherein said monolithic
ferrule body comprises a radially tapered nose portion adjacent the first
end of said monolithic ferrule body, said radially tapered nose portion
having an outer diameter which decreases in a longitudinal direction
toward the first end of said monolithic ferrule body.
Description
FIELD OF THE INVENTION
The present invention relates generally to ferrules and associated optical
fiber connectors and, more particularly, to ferrules and associated
optical fiber connectors which receive and position multiple optical
fibers.
BACKGROUND OF THE INVENTION
Optical fibers are widely used in a variety of applications, including the
telecommunications industry in which optical fibers are employed in a
number of telephony and data transmission applications. Due, at least in
part, to the extremely wide bandwidth and the low noise operation provided
by optical fibers, the use of optical fibers and the variety of
applications in which optical fibers are utilized are continuing to
increase. For example, optical fibers no longer serve merely as the medium
for long distance signal transmissions, but are increasingly routed
directly to the home or, in some instances, directly to a desk or other
work location.
In order to effectively route and install optical fibers, efficient methods
of coupling optical fibers, such as to other optical fibers, to a patch
panel in a telephone central office or in an office building or to various
remote terminals or pedestals, are required. Accordingly, a variety of
optical fiber connectors have been developed which can be mounted to end
portions of one or more optical fibers to facilitate connection or
coupling of the optical fibers.
In order to further facilitate the connection of one or more optical
fibers, a number of standard optical fiber connectors have been developed.
These standard optical fiber connectors provide a predetermined type of
connector interface such that the optical fiber connector or other type of
terminal to which the standard optical fiber connector will be coupled can
be appropriately designed to mate therewith. In particular, a number of
different types of standard optical fiber connectors, such as the SC, FC,
ST and D4 connectors, have been developed.
Each of these standard optical fiber connectors is designed to receive and
maintain a single optical fiber in a predetermined position during
interconnection, such as with another optical fiber connector or other
types of terminals. In ever increasing numbers of applications, however,
it is desirable to transmit and receive optical signals via two or more
optical fibers. For example, it is desirable in many fiber to the desk
applications to route a pair of optical fibers to the desk in order to
concurrently send and receive optical signals.
In order to provide two or more optical fibers for these and other
applications, a number of optical fiber connectors have been developed
which receive and maintain two or more optical fibers in respective
predetermined positions during interconnection. For example, the ESCON.TM.
connector and the FCS.TM. connector have been developed. These connectors
include a pair of conventional ferrules, each of which receive and
maintain a single optical fiber in a predetermined position during
interconnection. The ESCON.TM. and FCS.TM. connectors also include a
housing or yoke which surrounds and supports the ferrules in a
side-by-side relationship. Accordingly, these optical fiber connectors can
provide for the simultaneous connection of two or more optical fibers as
known to those skilled in the art. However, these optical fiber
connectors, such as the ESCON.TM. and FCS.TM. connectors, are generally
relatively large since they include at least two conventional ferrules
positioned in a side-by-side relationship.
In addition, several other types of customized or nonstandard optical fiber
connectors have been developed to receive and maintain two or more optical
fibers in predetermined positions during interconnection. For example,
U.S. Pat. No. 5,064,268 to Roger L. Morency, et al. discloses a fiber
optic connector plug which provides for the connection of a plurality of
optical fibers in high pressure environments. In particular, the fiber
optic connector of the Morency '268 patent defines an internal cavity in
which a number of components for aligning and positioning the optical
fibers are disposed. These components include a precision insert which
defines a number of axial passages through which the optical fibers are
inserted. The internal cavity of the fiber optic connector plug of the
Morency '268 patent is also filled with several different types of
encapsulating resins in order to properly position and seal the optical
fibers within the fiber optic connector plug.
U.S. Pat. No. 4,898,449 to Laurentius C. J. Vroomen, et al. also discloses
a multi-component optical fiber connector which receives and positions a
plurality of optical fibers. The optical fiber connector of the Vroomen
'449 patent includes a fiber holder which is inserted in the front end of
the optical fiber connector to maintain the optical fibers in the proper
positions. In addition, the rear portion of the optical fiber connector of
the Vroomen '449 patent is filled with a molding mass of a suitable
synthetic resin.
Other nonstandard, multi-component optical fiber connectors for
interconnecting a plurality of optical fibers are described in U.S. Pat.
Nos. 5,125,055 and 5,123,072 to Norihide Kawanami, et al. The optical
fiber connectors of the Kawanami '055 and '072 patents include a sleeve in
which a plurality of lengthwise extending pins are disposed. The pins are
generally circular in lateral cross-section so as to define a number of
lengthwise extending passageways therebetween. Accordingly, a plurality of
optical fibers can extend through respective ones of the lengthwise
extending passageways and can be maintained in predetermined positions
during interconnection with other optical fibers or other types of
terminals.
U.S. Pat. No. 5,093,881 to Bruno Bortolin, et al. discloses another type of
multi-component optical fiber connector. In particular, the optical fiber
connector of the Bortolin '888 patent includes a ferrule formed by a pair
of complimentary ferrule elements. Each ferrule element defines a recess
in which an optical fiber ribbon cable can be disposed. Each ferrule
element also defines a number of grooves through which the individual
optical fibers of the ribbon cable can extend. The ferrule elements of the
Bortolin '881 patent are adapted to mate in a predetermined aligned
relationship such that the respective recesses and grooves are aligned.
Accordingly, a plurality of optical fibers can be simultaneously connected
by the optical fiber connector of the Bortolin '881 patent. However, the
optical fiber connector of the Bortolin '881 patent does require a pair of
complimentary ferrule elements as described above, each of which includes
a recess and a number of precisely formed grooves for receiving and
aligning the optical fibers.
Finally, U.S. Pat. No. 5,214,730 to Shinji Nagasawa, et al. describes an
optical fiber connector for receiving and positioning a plurality of
optical fibers such that the optical fibers can be simultaneously
connected. The optical fiber connector of the Nagasawa '730 patent
includes a number of lengthwise extending, laterally spaced apart
passageways through which respective ones of the optical fibers extend. In
addition, the optical fiber connector of the Nagasawa '730 patent includes
a pair of guide pins for engaging respective apertures defined in the
front face of another optical fiber connector such that the pair of
optical fiber connectors can be maintained in a predetermined aligned
relationship.
The optical fiber connector of the Nagasawa '730 patent is generally
rectangular in lateral cross-section, thereby potentially limiting the
number of applications in which the optical fiber connector can be
effectively utilized since, in some instances, an optical fiber connector
having a generally circular shape in lateral cross-section is required in
order to appropriately mate with another optical fiber connector or other
type of terminal. In addition, the optical fiber connector of the Nagasawa
'730 patent is typically formed of a thermosetting material which
solidifies upon heating, thereby requiring relatively sophisticated
fabrication processes in order to solidify the thermosetting material into
the predetermined shape of the optical fiber connector.
Therefore, while a number of customized or nonstandard optical fiber
connectors have been developed to receive and maintain a number of optical
fibers in position during interconnection, these optical fiber connectors
typically include multiple components, such as multiple ferrules, which
must be assembled to form the optical fiber connector. Due to the multiple
components which must generally be precisely aligned, the assembly process
can be relatively complicated and the resulting cost of the nonstandard
optical fiber connectors can be correspondingly increased. In addition,
due to the customized or nonstandard designs of these optical fiber
connectors, the optical fiber connectors typically cannot mate with
standard optical fiber connectors or with terminals which have been
designed to mate with standard optical fiber connectors. Further, the
relatively large size of a number of the nonstandard optical fiber
connectors described above limits the applications in which such optical
fiber connectors can be employed since they may be unable to mate with
other optical fiber connectors or other types of terminals in areas of
limited access.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved
optical fiber connector for simultaneously connecting a plurality of
optical fibers.
It is another object of the present invention to provide an improved
ferrule for receiving and maintaining a plurality of optical fibers in
respective predetermined positions prior to and during interconnection.
It is a further object of the present invention to provide a monolithic
ferrule for receiving and maintaining a plurality of optical fibers in
respective predetermined positions relative to the connector housing of a
standard optical fiber connector.
These and other objects are provided, according to the present invention,
by an optical fiber connector including a connector housing and a
monolithic ferrule disposed within the connector housing which maintains a
plurality of optical fibers in respective predetermined positions relative
to the connector housing. The connector housing defines an internal cavity
opening through the first and second ends of the connector housing in
which the monolithic ferrule is disposed. According to one advantageous
embodiment, the connector housing has a size and shape which matches the
predetermined size and shape of the connector housing of a standard
optical fiber connector, such as an SC, FC, ST or D4 optical fiber
connector. Accordingly, the optical fiber connector of this embodiment of
the present invention can be effectively coupled to other standard optical
fiber connectors or other types of terminals adapted to mate with standard
optical fiber connectors.
The monolithic ferrule of the present invention includes a monolithic
ferrule body, typically formed of a thermoplastic or ceramic material,
which extends longitudinally between opposed first and second ends and
which defines an internal cavity for receiving the plurality of optical
fibers. The internal cavity opens through both the second end of the
monolithic ferrule body and extends longitudinally through at least a
portion of the monolithic ferrule body. The monolithic ferrule body also
defines a number of longitudinal bores extending between the first end of
the monolithic ferrule body and the internal cavity defined therein. The
longitudinal bores are adapted to receive respective ones of the plurality
of optical fibers such that the optical fibers are maintained in
respective predetermined positions relative to the monolithic ferrule
body.
The first end of the monolithic ferrule body is preferably exposed through
the first end of the connector housing. Thus, the optical fibers
maintained within the longitudinal bores of the monolithic ferrule body
can also be exposed through the first end of the connector housing so as
to facilitate connection of the optical fibers, such as with other optical
fibers.
The internal cavity can include first and second internal cavity portions
adjacent the first and second ends of the monolithic ferrule body,
respectively. In order to facilitate the insertion of the plurality of
optical fibers within the internal cavity defined by the monolithic
ferrule body, the size of the second internal cavity portion adjacent the
second end of the monolithic ferrule body is preferably greater than the
size of the first internal cavity portion. The second internal cavity
portion can also include a radially tapered portion adjacent the second
end of the monolithic ferrule body to further facilitate the insertion of
the plurality of optical fibers therein.
The monolithic ferrule body of one embodiment in the present invention also
includes a radially tapered nose portion adjacent the first end of the
monolithic ferrule body. The radially tapered nose portion has an outer
diameter which decreases in a longitudinal direction toward the first end
of the monolithic ferrule body. Accordingly, the connection of an optical
fiber connector which includes the monolithic ferrule body of this
embodiment is simplified since the radially tapered nose portion serves to
guide the monolithic ferrule body into proper alignment with the ferrule
of the optical fiber connector with which connection is being made and,
more particularly, with the optical fibers of the optical fiber connector
with which connection is being made.
An optical fiber connector of one advantageous embodiment of the present
invention also includes an annular alignment key mounted to the monolithic
ferrule and extending radially outward. The alignment key includes a
position indicator and is adapted to mate with the connector housing such
that the monolithic ferrule is held in a predetermined position therein.
Accordingly, the plurality of optical fibers received by the longitudinal
bores defined by the monolithic ferrule are maintained in respective
predetermined positions relative to the connector housing since the
plurality of longitudinal bores are positioned in a predetermined angular
relationship to the position indicator of the alignment key and,
consequently, to the connector housing. According to one embodiment, the
monolithic ferrule includes the annular alignment key such that the
alignment key is an integral portion of the monolithic ferrule body and is
formed of the same material from which the monolithic ferrule body is
formed.
The monolithic ferrule can also include ferrule alignment means for
aligning the monolithic ferrule with another ferrule such that the optical
fibers received by the longitudinal bores defined by the monolithic
ferrule are aligned with the optical fibers secured within the other
ferrule. According to one embodiment, the ferrule alignment means includes
interlocking means for rotatably engaging both aligned ferrules and a
ferrule sleeve. The ferrule sleeve has opposed first and second ends and
can be mounted about both the first end of the monolithic ferrule body and
an end portion of the other ferrule body. Accordingly, the ferrule bodies
are rotatably engaged by the ferrule sleeve in the predetermined aligned
relationship.
According to one embodiment, the ferrule alignment means and, more
specifically, the interlocking means includes a slot defined by the
monolithic ferrule body and extending both radially inward and
longitudinally along the exterior surface thereof. The slot is adapted to
receive a rib which extends longitudinally along and radially into a bore
defined by the ferrule sleeve. Thus, the monolithic ferrule body can be
rotatably engaged in a predetermined position relative to the ferrule
sleeve and, in turn, to the other ferrule rotatably engaged by the ferrule
sleeve.
Accordingly, the monolithic ferrule of the present invention is simplified
since the monolithic ferrule is formed from a single piece of material
and, consequently, is not comprised of multiple components which must be
separately fabricated and then assembled in a predetermined aligned
relationship. Correspondingly, the assembly of the optical fiber connector
is also simplified since the monolithic ferrule is formed from a single
piece of material. Further, the monolithic ferrule of the present
invention is sized and shaped so that the monolithic ferrule can be
disposed within a connector housing of an optical fiber connector which
has a standard size, thereby allowing multiple optical fibers to be
connected by a single standard optical fiber connector of the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of one embodiment of an optical fiber
connector of the present invention which includes a monolithic ferrule
extending through a first end of the connector housing of the optical
fiber connector.
FIG. 2 is a longitudinal cross-sectional view of the embodiment of the
optical fiber connector of the present invention shown in FIG. 1 and taken
along line 2--2.
FIG. 3 is a perspective view of one embodiment of a monolithic ferrule
according to the present invention.
FIG. 4 is a longitudinal cross-sectional view of the embodiment of the
monolithic ferrule of the present invention shown in FIG. 3 and taken
along line 4--4 which illustrates the internal cavity and the plurality of
longitudinal bores defined by the monolithic ferrule.
FIG. 5 is an exploded perspective view of one embodiment of a ferrule
assembly of the present invention which includes a monolithic ferrule and
a ferrule sleeve adapted to rotatably couple the monolithic ferrule with
another ferrule in a predetermined aligned relationship.
FIG. 6 is a lateral cross-sectional view of an assembled ferrule assembly
including a monolithic ferrule and a ferrule sleeve which illustrates the
interlocking relationship of the slot defined by the monolithic ferrule
and the inwardly extending rib of the ferrule sleeve.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will now be described more fully hereinafter with
reference to the accompanying drawings, in which a preferred embodiment of
the invention is shown. This invention may, however, be embodied in many
different forms and should not be construed as limited to the embodiments
set forth herein; rather, this embodiment is provided so that this
disclosure will be thorough and complete and will fully convey the scope
of the invention to those skilled in the art. Like numbers refer to like
elements throughout.
Referring now to FIG. 1, an optical fiber connector 10 according to one
embodiment of the present invention is illustrated. The optical fiber
connector includes a monolithic ferrule 12 for receiving and maintaining a
plurality of optical fibers in respective predetermined positions. As
shown in FIGS. 3 and 4, The monolithic ferrule includes a monolithic
ferrule body extending longitudinally between first and second opposed
ends 12a and 12b, respectively. The monolithic ferrule body also defines
an internal cavity 14 for receiving the plurality of optical fibers. As
shown in more detail in FIG. 4, the internal cavity opens through the
second end of the monolithic ferrule body and extends longitudinally
through at least a portion of the monolithic ferrule body.
In one advantageous embodiment, the internal cavity 14 defined by the
monolithic ferrule body includes first and second internal cavity portions
14a and 14b adjacent the first and second ends of the monolithic ferrule
body 12a and 12b, respectively. The first and second internal cavity
portions have respective predetermined sizes and, more particularly, are
preferably sized such that the second internal cavity portion is larger
than the first internal cavity portion. Accordingly, the plurality of
optical fibers can be readily inserted through the opening defined in the
second end of the monolithic ferrule 12 and into the internal cavity
defined therein.
The monolithic ferrule body of the present invention also defines a
plurality of longitudinal bores 16 extending between the first end 12a of
the monolithic ferrule body and the internal cavity 14 defined therein.
The longitudinal bores are sized and shaped to receive respective ones of
the plurality of optical fibers. Thus, the optical fibers are maintained
within the longitudinal bores in respective predetermined positions
relative to the monolithic ferrule body. For example, a monolithic ferrule
body having a pair of longitudinal bores is shown in FIGS. 3 and 4 and is
adapted to receive a pair of optical fibers. However, the monolithic
ferrule body can include any number of longitudinal bores so as to receive
any number of optical fibers without departing from the spirit and scope
of the present invention.
Therefore, a plurality of optical fibers, typically arranged in an optical
fiber cable, such as an optical fiber ribbon cable, can be inserted
through the opening defined in the second end 12b of the monolithic
ferrule body and into the internal cavity 14 defined therein, individual
optical fibers can then be extended through respective ones of the
longitudinal bores 16 defined by monolithic ferrule body and opening
through the first end 12a thereof.
The monolithic ferrule 12 of the present invention is comprised of a single
piece of material. For example, the monolithic ferrule can be formed of a
thermoplastic material, such as a polyetherimidresin, the ULTEM.RTM.
material available from General Electric Company or the RADEL.RTM.
material available from Amoco Corporation. Alternatively, the monolithic
ferrule can be formed of a ceramic material, such as a glass impregnated
ceramic material.
In addition, the monolithic ferrule 12 can be formed in a variety of
manners. For example, the monolithic ferrule can be molded, such as by an
injection molding process, from a thermoplastic material. Alternatively, a
block of material can be machined, such as by drilling and grinding, to
form a monolithic ferrule of the desired shape. However, the monolithic
ferrule can be formed by other methods known to those skilled in the art,
without departing from the spirit and scope of the present invention.
As shown in FIGS. 1 and 2, the optical fiber connector 10 of the present
invention also includes a connector housing 20 having opposed first and
second ends 20a and 20b, respectively, and defining an internal cavity 22
opening through both ends thereof. The monolithic ferrule 12 of the
present invention is preferably sized and shaped to be disposed within the
internal cavity defined by the connector housing of an optical fiber
connector having a standard size and shape, such as an SC connector, an FC
connector, an ST connector or a D4 connector. In particular, the
monolithic ferrule is preferably disposed within the internal cavity of
the connector housing such that at least the first end 12a of the
monolithic ferrule is exposed through the first end of the connector
housing as best shown in FIGS. 1 and 2. As also illustrated, the plurality
of optical fibers, such as a fiber optic cable, preferably extends into
the internal cavity of the connector housing through the second end
thereof.
The monolithic ferrule 12 of the present invention is preferably maintained
in a predetermined position relative to the connector housing 20.
Accordingly, the optical fiber connector 10 of one embodiment can include
an annular alignment key 24 which is mounted in a fixed position to the
monolithic ferrule. As illustrated, the annular alignment key extends
radially outward from the monolithic ferrule and includes a position
indicator 26 which is adapted to mate with the connector housing such that
the monolithic ferrule is held in a predetermined position therein. In
particular, as shown in FIG. 3, the position indicator can include a slot
defined by the alignment key which is engaged by a corresponding element
of the connector housing, such as a rib or other projection, such that the
connector housing and the monolithic ferrule are effectively coupled.
As shown in FIGS. 3 and 4, the plurality of longitudinal bores 16 defined
by the monolithic ferrule 12 are also positioned in a predetermined
angular relationship to the position indicator 26 of the alignment key 24.
Thus, the optical fibers received by longitudinal bores are maintained in
respective predetermined positions relative to the position indicator of
the alignment key and, in turn, to the connector housing 20.
Typically, an annular alignment key 24 is provided to prevent rotation of
the monolithic ferrule 12 after the assembled optical fiber connector 10
has been installed in the field, such as to a coupling sleeve or other
type of connector. As known to those skilled in the art, rotation of the
optical fiber connector could damage the end face 12a of the monolithic
ferrule. The annular alignment key also can provide an angular position
indication for use in aligning the eccentricity of the fiber-ferrule
assembly to maximize optical power transmission for a mated pair of
optical fiber connectors. Such angular position indication can be
established by optical detection during rotation. By preventing relative
rotation of the monolithic ferrule and the connector housing 20 of the
optical fiber connector, the annular alignment key also serves to maintain
the predetermined alignment of the plurality of optical fibers with the
other optical fibers to which the optical fiber connector is connected.
In one advantageous embodiment, the monolithic ferrule 12 also includes the
annular alignment key 24 such that the alignment key is an integral
portion of the monolithic ferrule body. Accordingly, the annular alignment
key of this embodiment is formed of the same material from which the
monolithic ferrule is comprised. However, the annular alignment key 24 can
be formed as a separate component without departing from the spirit and
scope of the present invention. For example, the alignment key can be
press-fit on the monolithic ferrule or can be secured to the monolithic
ferrule, such as with an epoxy.
In addition, while an optical fiber connector 10 having an annular
alignment key 24 is illustrated and described herein, the optical fiber
connector can include other means of coupling the connector housing 20 and
the monolithic ferrule 12, including sizing the monolithic ferrule and the
internal cavity 22 of the connector housing such that the monolithic
ferrule and the connector housing are frictionally engaged, without
departing from the spirit and scope of the present invention.
As shown in FIG. 2, the optical fiber connector 10 can also include a
number of other components for securing the monolithic ferrule 12 within
the connector housing 20 as known to those skilled in the art. For
example, in the embodiment illustrated in FIGS. 1 and 2, the optical fiber
connector can also include a lead in tube 40, typically comprised of a
metallic material, which is disposed within the internal cavity 22 of the
connector housing. A first end of the lead in tube is also preferably
inserted through the opening defined in the second end 12b of the
monolithic ferrule and into the second portion 22b of the internal cavity
defined therein. The lead in tube further facilitates the insertion of the
plurality of optical fibers into the monolithic ferrule of the present
invention by directing the optical fibers longitudinally into the internal
cavity of the monolithic ferrule.
The optical fiber connector 10 of this embodiment also includes a crimp
body 42 which surrounds the lead in tube 40 and is mounted to the second
end 12b of the monolithic ferrule 12. For example, the crimp body can be
mounted in a press fit relationship to the second end of the monolithic
ferrule or can be secured, such as with an epoxy, thereto. As illustrated,
the optical fiber connector can also include a boot 48, typically
comprised of a plastic material, which surrounds and, in some embodiments,
threadably engages the crimp body so as to further protect the optical
fiber cable. In particular, in embodiments in which the optical fiber
connector of the present invention is adapted to mount to end portions of
an optical fiber cable which includes one or more lengthwise extending
strength members, such as aramid fibers, the strength members can be held
securely between the crimp body and the boot in a manner which will
protect the optical fiber connector assembly from subsequent axial forces
(e.g., tension and torsion) to which the optical fiber cable is subjected.
Although not illustrated, a crimp band, typically comprised of KEVLAR.RTM.
material, can also be secured about the strength members of the optical
fiber cable and the underlying crimp body in order to further protect the
optical fiber connector assembly.
As also illustrated in FIG. 2, the connector housing 20 of this embodiment
of the optical fiber connector 10 can be comprised of two components,
namely, a coupler 44 and an inner housing 46. The coupler is typically
comprised of a plastic material and defines an internal cavity extending
longitudinally therethrough. The annular inner housing is also typically
comprised of a plastic material and is disposed in a fixed position within
the internal cavity defined by the coupler and, more particularly, in a
fixed position adjacent the first end 20a of the connector housing 20. As
illustrated, the inner housing is adapted to engage the annular alignment
key 24 such that monolithic ferrule 12 is held in a predetermined position
relative to the connector housing as described above.
The optical fiber connector 10 of the present invention can be connected to
a variety of other optical fiber connectors, typically via a coupling
sleeve, and other types of terminals in order to interconnect the
plurality of optical fibers held by the monolithic ferrule 12 with other
optical fibers, thereby enabling optical signals to be efficiently
transmitted between the aligned optical fibers. Thus, in one advantageous
embodiment, the monolithic ferrule 12 also includes ferrule alignment
means for aligning the optical fibers received by the longitudinal bores
16 defined by the monolithic ferrule with the other optical fibers, such
as the optical fibers secured within another ferrule.
In embodiments of the present invention in which the optical fiber
connector 10 is mated with another optical fiber connector, the monolithic
ferrule 12 can be one component of a ferrule assembly. In addition to the
monolithic ferrule, the ferrule assembly of the present invention includes
a coupling sleeve and, more particularly, a ferrule sleeve 30.
As shown in FIGS. 5 and 6, the ferrule sleeve 30 has opposed first and
second ends 30a and 30b, respectively, and defines a bore 32 extending
longitudinally therethrough and opening through both ends. More
particularly, the bore defined by the ferrule sleeve is sized and shaped
to receive a portion of the monolithic ferrule body and, more
particularly, to receive the first end 12a of the monolithic ferrule body
within the first end of the ferrule sleeve. In addition, the second end of
the ferrule sleeve is capable of being mounted about an end portion of
another ferrule such that both ferrules are held therein.
The ferrule alignment means of the monolithic ferrule 12 of this embodiment
preferably includes interlocking means for rotatably engaging the ferrule
sleeve 30 and the monolithic ferrule such that the rotatably engaged
ferrule bodies are maintained in a predetermined aligned relationship.
More specifically, the monolithic ferrule 12 and the other ferrule which
are rotatably engaged by the ferrule sleeve are preferably maintained in a
predetermined aligned relationship such that each of the optical fibers
extending through the first end 12a of the monolithic ferrule are aligned
with corresponding optical fibers secured within the other ferrule which
is rotatably engaged by the ferrule sleeve. Consequently, optical signals
can be efficiently transmitted between the corresponding optical fibers of
the rotatably engaged ferrule bodies.
For example, the ferrule alignment means and, more particularly, the
interlocking means can include a slot 34 defined by the monolithic ferrule
body and extending both radially inward and longitudinally along the
exterior surface thereof. According to this embodiment, the ferrule sleeve
30 also preferably includes a rib 36 extending longitudinally along and
radially into the bore 32 defined by the ferrule sleeve 30. Accordingly,
the rib of the ferrule sleeve can engage the corresponding slot defined by
the monolithic ferrule body such that the monolithic ferrule body is
rotatably coupled to the ferrule sleeve. The rib also preferably engages a
slot defined by the other ferrule received by the ferrule sleeve such that
both ferrules are rotatably coupled to the ferrule sleeve in the
predetermined aligned relationship.
While a ferrule assembly having a monolithic ferrule 12 in which a slot 34
is defined and a ferrule sleeve 30 having a radially inwardly extending
rib 36 is illustrated and described herein, the ferrule assembly can
include other interlocking means for rotatably engaging the ferrule sleeve
and the ferrule bodies without departing from the spirit and scope of the
present invention. For example, the monolithic ferrule can include a rib
extending both radially outward and longitudinally along the exterior
surface thereof which is adapted to engage a corresponding slot defined
longitudinally along the interior surface of the ferrule sleeve.
Accordingly, an optical fiber connector 10 including the monolithic ferrule
12 of the present invention can be connected, such as to another optical
fiber connector and, more particularly, to another ferrule, by inserting
end portions of the ferrules of both optical fiber connectors into opposed
ends of the ferrule sleeve 30. As described above, the ferrule sleeve and
the ferrule bodies are rotatably engaged by the interlocking means of the
ferrule assembly in a predetermined aligned relationship such that the
optical fibers held by each of the ferrules are appropriately aligned.
While a monolithic ferrule 12 having ferrule alignment means which includes
interlocking means, such as a longitudinally extending slot 34, is
described and illustrated herein, the ferrule alignment means can include
a variety of other features for aligning the monolithic ferrule with
another ferrule and, in turn, for aligning the optical fibers held by each
of the respective ferrules. In addition, the ferrule alignment means can
align the monolithic ferrule, such as with another ferrule, both in
embodiments in which the monolithic ferrule is one component of a ferrule
assembly as described above as well as in embodiments in which the
monolithic ferrule is aligned with another ferrule without the assistance
of a ferrule sleeve 30.
For example, the ferrule alignment means can include a plurality of
apertures defined by the monolithic ferrule body and opening through the
first end 12a thereof. The apertures defined by the monolithic ferrule
body of this embodiment are adapted to receive respective ones of a
plurality of guide pins such that the plurality of guide pins extend
outwardly from the first end of the monolithic ferrule body. As known to
those skilled in the art, the guide pins can be received and engaged by
apertures defined by another ferrule body and opening through the first
end thereof so as to rotatably engage the monolithic ferrule body and the
other ferrule body. Accordingly, the ferrule bodies and, more
particularly, the optical fibers received by the ferrule bodies, can be
maintained in a predetermined aligned relationship without the assistance
of a ferrule sleeve 30.
Accordingly, the fabrication and assembly of the monolithic ferrule 12 of
the present invention can be simplified since the monolithic ferrule is
formed from a single piece of material and, consequently, is not comprised
of multiple components which must be separately fabricated and then
assembled in a predetermined aligned relationship. Correspondingly, the
fabrication and assembly of the optical fiber connector 10 of the present
invention is also simplified since the monolithic ferrule is formed from a
single piece of material. Further, the monolithic ferrule of the present
invention is sized and shaped so that the monolithic ferrule can be
disposed within a connector housing 20 of an optical fiber connector which
has a standard size, thereby allowing multiple optical fibers to be
connected by a single standard optical fiber connector of the present
invention.
In the drawings and the specification, there has been set forth preferred
embodiments of the invention and, although specific terms are employed,
the terms are used in a generic and descriptive sense only and not for
purpose of limitation, the scope of the invention being set forth in the
following claims.
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